import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

import '../core/env.dart';
import '../core/models.dart';
import '../data/user_library.dart';
import '../features/artist/artist_screen.dart';
import '../features/auth/login_screen.dart';
import '../features/downloads/downloads_screen.dart';
import '../features/explore/explore_screen.dart';
import '../features/explore/occasion_screen.dart';
import '../features/home/home_screen.dart';
import '../features/library/library_screen.dart';
import '../features/profile/profile_screen.dart';
import '../features/player/now_playing_screen.dart';
import '../features/about/about_screen.dart';
import '../features/album/album_screen.dart';
import '../features/search/search_screen.dart';
import '../features/settings/document_screen.dart';
import '../features/settings/help_screen.dart';
import '../features/settings/report_screen.dart';
import '../features/settings/settings_screen.dart';
import '../features/support/support_screen.dart';
import '../features/welcome/splash_screen.dart';
import '../shared/widgets/app_shell.dart';

/// Whether the welcome + sign-in screens have been seen on this device.
class Onboarding extends Notifier<bool> {
  static const _key = 'onboarding_done';

  @override
  bool build() => ref.watch(sharedPrefsProvider).getBool(_key) ?? false;

  void complete() {
    state = true;
    ref.read(sharedPrefsProvider).setBool(_key, true);
  }
}

final onboardingProvider = NotifierProvider<Onboarding, bool>(Onboarding.new);

/// Re-runs the router redirect when someone signs in or out.
class _AuthRefresh extends ChangeNotifier {
  _AuthRefresh() {
    if (Env.hasSupabase) {
      _sub = Supabase.instance.client.auth.onAuthStateChange.listen((_) => notifyListeners());
    }
  }

  StreamSubscription<AuthState>? _sub;

  @override
  void dispose() {
    _sub?.cancel();
    super.dispose();
  }
}

/// Signed in to the server. Guests (and demo builds with no server) are not.
bool get isSignedIn => Env.hasSupabase && Supabase.instance.client.auth.currentSession != null;

final routerProvider = Provider<GoRouter>((ref) {
  final onboarded = ref.read(onboardingProvider);
  final authRefresh = _AuthRefresh();
  ref.onDispose(authRefresh.dispose);
  return GoRouter(
    initialLocation: onboarded ? '/home' : '/welcome',
    refreshListenable: authRefresh,
    // Guests can browse (with 30-second previews); the profile needs an account.
    redirect: (_, state) {
      final at = state.matchedLocation;
      if (!isSignedIn && at == '/profile') return '/login';
      if (isSignedIn && at == '/login') return '/home';
      return null;
    },
    routes: [
      GoRoute(path: '/welcome', builder: (_, _) => const SplashScreen()),
      GoRoute(
        path: '/login',
        builder: (_, state) => LoginScreen(startWithSignUp: state.uri.queryParameters['mode'] == 'signup'),
      ),
      GoRoute(path: '/profile', builder: (_, _) => const ProfileScreen()),
      GoRoute(path: '/about', builder: (_, _) => const AboutScreen()),
      GoRoute(path: '/settings', builder: (_, _) => const SettingsScreen()),
      GoRoute(path: '/help', builder: (_, _) => const HelpScreen()),
      GoRoute(path: '/support', builder: (_, _) => const SupportScreen()),
      GoRoute(
        path: '/privacy',
        builder: (_, _) => const DocumentScreen(title: 'Privacy Policy', asset: 'assets/legal/privacy.md'),
      ),
      GoRoute(
        path: '/terms',
        builder: (_, _) => const DocumentScreen(title: 'Terms of Use', asset: 'assets/legal/terms.md'),
      ),
      GoRoute(
        path: '/report',
        builder: (_, state) => ReportScreen(trackId: state.uri.queryParameters['track']),
      ),
      StatefulShellRoute.indexedStack(
        builder: (_, _, shell) => AppShell(shell: shell),
        branches: [
          StatefulShellBranch(
            routes: [
              GoRoute(path: '/home', builder: (_, _) => const HomeScreen()),
            ],
          ),
          StatefulShellBranch(
            routes: [
              GoRoute(
                path: '/explore',
                builder: (_, _) => const ExploreScreen(),
              ),
            ],
          ),
          StatefulShellBranch(
            routes: [
              GoRoute(
                path: '/library',
                builder: (_, _) => const LibraryScreen(),
              ),
            ],
          ),
          StatefulShellBranch(
            routes: [
              GoRoute(
                path: '/downloads',
                builder: (_, _) => const DownloadsScreen(),
              ),
            ],
          ),
        ],
      ),
      GoRoute(path: '/search', builder: (_, _) => const SearchScreen()),
      GoRoute(
        path: '/artist/:id',
        builder: (_, state) =>
            ArtistScreen(artistId: state.pathParameters['id']!),
      ),
      GoRoute(
        path: '/album/:id',
        builder: (_, state) =>
            AlbumScreen(albumId: state.pathParameters['id']!),
      ),
      GoRoute(
        path: '/occasion/:id',
        builder: (_, state) => OccasionScreen(
          occasion: Occasion.fromId(state.pathParameters['id']),
        ),
      ),
      GoRoute(
        path: '/player',
        pageBuilder: (_, state) => CustomTransitionPage(
          key: state.pageKey,
          fullscreenDialog: true,
          child: const NowPlayingScreen(),
          transitionsBuilder: (_, animation, _, child) => SlideTransition(
            position: Tween(
              begin: const Offset(0, 1),
              end: Offset.zero,
            ).chain(CurveTween(curve: Curves.easeOutCubic)).animate(animation),
            child: child,
          ),
        ),
      ),
    ],
  );
});